A tab is typically secured to a can end and the can end is opened by lifting a lift portion of the tab by pulling upwards on the tab so as to pivot the tab about a rivet which secures the tab to the can end. Lifting the lift portion of the tab upwards fractures a score line disposed on the can end which permits the end-user to access the contents of the can end.
Oftentimes, the prior art tab is a rigid member wherein the rigidity of the tab does not enable easy opening of the can end with the tab. Prior to use, the tab is generally in a flat orientation, parallel to the plane of the end panel of the can end. Lifting the tab requires the end-user to reach with their finger between the tab and the seam of a can end to exert upward lift on the bottom side of the tab. Such an approach can create difficulty for the end-user to acquire proper leverage to open the can end. The difficulty can become more pronounced if the end-user has long fingernails or weak fingers that make it awkward for the end-user to reach between the tab and the seam of the can end.
Several patents have attempted to overcome this issue by having a flexible portion within the tab. Such an approach enables the end-user to initially pivot a lift portion of the tab upwards about the flexible portion without initially pivoting the tab about the rivet and incurring resistance from the can end. Once the tab is bent in this manner, the end-user can gain full leverage on the tab to pivot the tab along the rivet that stakes the tab to the can end and sever the score line on the can end without being encumbered by the close confinement of the end panel or the seam.
U.S. Pat. No. 6,026,971 to Lundgren discloses a pull tab with a flexible portion, wherein the flexible portion transects the pull tab, dividing it into a nose portion and a lift portion. The upward bending of the pull tab about the flexible portion enables a user to gain leverage when opening a can end by first bending the lift portion upward while the nose portion remains still. The flexible portion, however, completely extends from one side of the pull tab to the other, creating a full line of demarcation. Pull tabs with full lines of demarcation tend to break off during initial upward lift of the lift portion or during pushing of the lift portion downward after use.
U.S. Pat. No. 6,575,325 to Dickie et al. discloses a pull tab opener with a nose portion and a lift portion separated by a flexible crease line, where the lift portion is articuable in relation to the nose portion. The nose and lift portion are connected by at least a pair of angular, hinge-like protrusions upstanding from the pull tab. The protrusions help keep the pull tab from breaking off along the crease line when the pull tab is lifted upward to open a can end; however, pushing of the pull tab downward runs the risk of breaking off the lift portion since the crease line is not reinforced to effectively permit flexible downward movement of the pull tab about the crease line. Also, the protrusions are difficult to manufacture and would substantially increase the cost of manufacture of the pull tab both in the amount of material used and in the equipment necessary to form the pull tabs. Additionally, the protrusions could interfere with the bottom of the dome of a can where the cans are vertically stacked on top of each another in storage. If the protrusions are too high, it would be difficult to stack cans having such a can end seamed thereon leading to storage problems with this can end.
U.S. Pat. No. 3,499,573 to Adams discloses an opening system for removing an entire end panel of a container. The opening system includes a pull tab having notches on opposed sides of the pull tab, wherein the notches allow the pull tab to bend upward, enabling the user to get enough leverage to open the can and remove the end panel. The pull tab requires two rivets, however, surrounded by a mustache shaped score line on the product side of the can end, wherein the lifting of the pull tab severs a connection between one of the rivets and the pull tab. Further, a central area of the pull tab extends around the rivets. The solid nature of the tab and the extra rivets result in unnecessary resistance when opening the tab. Further, the excess material used to form the tab increases the cost of manufacturing the product.
There continues to be a need in the art for a tab that enables an end-user to bend the tab upward about a fulcrum with minimal resistance in order to gain leverage to sever a score line in a can end, and to thereafter push the tab downward back to a substantially flat position above the end panel without breaking off the lift portion.